


The Box

by savorvrymoment



Category: Supernatural
Genre: Alternate Universe - Always a Different Sex, Always Female Sam Winchester, F/M, Menstruation Kink, Sibling Incest
Language: English
Status: Completed
Published: 2019-10-14
Updated: 2019-10-14
Packaged: 2020-12-14 22:27:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,668
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21023231
Author URL: https://archiveofourown.org/users/savorvrymoment/pseuds/savorvrymoment
Summary: They’ve been back out on the road together for a couple of weeks, a couple of weeks since Dean took Sammy away from Stanford. And while maybe it should have occurred to Dean that eventually Sammy would have her period, would continue to have her period on a regular basis because she is agirl,it’s never actually crossed his mind.





	The Box

**Author's Note:**

> This was written back in 2010 for a kink bingo fill. I've been kinda getting back into SPN what with the final season. I figured I'd give this a quick edit and post it. Hope you enjoy! 
> 
> Comments and kudos are love<3

Dean is brought up short that morning when he walks into the little bathroom and sees the tampon box set next to the toilet. He stares for a moment, feeling entirely uncomfortable and forgetting that he’d gone in to take a piss in the first place. Then he turns around and walks back out into the motel room.  
  
They’ve been back out on the road together for a couple of weeks, a couple of weeks since Dean took Sammy away from Stanford. And while maybe it should have occurred to Dean that eventually Sammy would have her period, would continue to have her period on a regular basis because she is a _girl_, it’s never actually crossed his mind.  
  
Sammy is still lying in bed on her belly, her head turned to the side on the pillow, but she’s awake and regards Dean with sleepy eyes as he leaves the bathroom. She raises her eyebrows at him and asks, “You okay?”  
  
“There are tampons in there,” he blurts. He gets a blank stare from her in return. He presses on, “Are you on your period?”  
  
She lies still for a moment, looking at him in something resembling disbelief, before rolling up to sit and face him. “Yeah,” she answers eventually. “I’m not sure how that is your business. But I am…”  
  
Dean’s suddenly at a loss for words, but he still finds this unacceptable. “Your tampons are by the sink,” he points out again, for lack of anything better to say.  
  
She opens her mouth like she’s going to say something, then closes it, looking at him in confusion. And then infuriatingly, she grins. “You’re kidding me, right?” she says. “That box of tampons freak you out?”  
  
“No,” Dean insists petulantly. “Just—why do we have to look at them? Put them somewhere else.”  
  
He can tell immediately that this was the wrong thing to say. She narrows her eyes at him, her nose wrinkling. “Oh, because your smelly socks in the sink are such a joy to look at,” she snaps. “So are your dirty underwear wadded up on the floor. And the razor in the shower with your pubes on it—don’t even get me started on that…”  
  
“Hey,” Dean says, nostrils flaring. “Girls like it when you do a little landscaping down there.”  
  
“Okay,” she yells back, spreading her arms out. “But you still clean the damn razor off!”  
  
“Man, you are so PMSing,” Dean shoots back.  
  
“And you are so full of shit,” Sammy says, getting up out of bed in a snit. “Just shut up, would you? Just shut the fuck up.”  
  
“What is your problem?” Dean says, beginning to realize that he has actually pissed her off. Like really, seriously pissed her off.  
  
“You. You are my problem, twenty-four-seven,” she snaps, walking over to stand in front of him. He’s still leaning in the doorway to the bathroom, and she gestures wildly. “Can you get out of the way, I need to get in there. You know, to change my tampon. Because I’m on my period.”  
  
He glares at her for a second before stepping out of the way, and she storms inside, slamming the door in his face.  
  
“What a bitch,” he mumbles to himself.  
  
“I heard that!” she yells back through the door.  
  
Dean just rolls his eyes.  
  
~*~  
  
He gets over it eventually. It’s not like she gives in to him—she so rarely does—so he just ignores the telltale box that shows up monthly. He deals with a lot worse on a daily basis, anyway.  
  
And then a year later, they stumble over that mark that Sammy later tells him was inevitable, all things considered. She’s amazing in bed. It’s something Dean hadn’t really been expecting, truth be told. She’s Sammy; a little gangly, awkward at times, nerdy to boot. But then maybe he _should_ have expected it, because she’s also tough as nails, fierce and loyal and passionate.  
  
She’s a fan of being on top, Dean finds out quickly. She loves to ride him, her nails digging into his chest, likes to be a little rough. Except on nights when she's exhausted from the hunt, then she’ll fold herself over onto his chest, let him wrap his arms around her and brace his feet on the bed and thrust up into her. And the noises she makes muffled into the curve of his neck. God, the noises…  
  
With all of the trust and love he’s found, though, there’s still the nagging fact that she’s his sister, and this could all be disastrous. They’re careful—very, very careful—but the monthly box of tampons becomes reassurance that they don’t have anything to worry about. Or at least, they don’t have to worry about _that_.  
  
Not that the thought of her bleeding still doesn’t give him this weird churning feeling in his stomach, makes him want to take that stupid little box and hide it somewhere so he doesn’t have to look at it, but he doesn’t say anything. He doesn’t really want to get yelled at over it again. There’s a difference in giving Sammy shit over things that will make her roll her eyes and call him a jerk, and things that will turn her into a raving bitch. Dean tries to avoid the latter.  
  
He’s a man, though, and a Winchester. And sometimes he can’t help himself.  
  
It’s after a hunt, pretty late at night. He takes first shower, then props himself up in the bed while Sammy takes her own, busying himself thumbing through the channels as he listens to the water run in the bathroom. He settles on some late-night rerun, more occupied with picturing Sammy naked and covered with soap than actually watching the TV.  
  
She comes out of the bathroom momentarily, dressed in one of his t-shirts and a pair of plain black panties. She’s got a towel in her hand, rubbing it back and forth over her hair. She looks gorgeous, a hot mess, and like always, seeing his shirt on her brings out a possessive streak in him a mile wide.  
  
“I’ll get dressed again if you want to go out somewhere,” she offers, lowering the towel and shaking her hair out a bit. Dean can tell she doesn’t really want to go anywhere, is just offering for his sake. She looks tired, drained, maybe even a little sore.  
  
He shakes his head, pats the space next to him. “Let’s stay here for tonight,” he says. “S’been a long day.”  
  
She nods, looking a little relieved, and climbs up on the bed next to him. He smiles to himself at the warmth of her body, lets his hand settle on her hip as she leans against him and rests her head against his shoulder. She’s oddly feminine at times like these, curled up and cuddly, the guns and knives and holy water seemingly forgotten about.  
  
It’s silent and still between them for quite a while, Sammy’s breath ghosting against his skin, her hip warm under his hand. But then Sammy is easing a hand down his stomach, rubbing at his belly just below his navel and rucking his t-shirt up before sliding her hand into his boxer shorts.  
  
He sucks in a short breath, feeling himself start to harden in her hand, and tilts his face to the side to find her mouth. She’s there waiting for him, her lips warm and a little chapped, and he moves his hand from her hip to cup her cheek. The inside of her mouth tastes like their toothpaste.  
  
He goes to haul her on top of him, already wanting to be inside her, but he's left confused and frustrated when she resists. He tugs at her body a little more, trying to get her to roll with him and straddle him, but she seems content with just lazy kissing and giving him a handjob. He grunts against her mouth, mumbles, “Come on, Sammy…”  
  
She hesitates but acquiesces in the end, throwing a leg over his waist and looking down at him with lust-blown eyes. Her hair is starting to dry in messy tendrils, tangled where Dean's had his fingers wrapped up in it, and she’s flushed a light sex pink. He can see the tiny buds of her nipples the way his shirt is laying across her breasts, and he reaches forward to slide his hands up under the shirt, cupping her breasts. She gasps, pressing forward into his touch, and he leans forward to meet her, capturing her lips in a kiss.  
  
But then she’s pulling away, spreading his legs to settle down between them. He tries to pull her back into his lap, but she ducks away from his hands, pulls his cock out of his boxers. It’s a momentary distraction—Sammy pressing soft, wet kisses along his shaft then tonguing at the slit—but he wants all of her, wants to be buried in her with her body draped over him. He grabs at her shoulder, mumbles, “Sammy, come on. Want you.”  
  
She responds by flicking her eyes up to meet his face then taking as much of him as she can in her mouth, hand wrapped around the base. She hums, her tongue laving around the underside of his dick, and he groans, still tries to reach for her. “Want you,” he gasps, trying not to thrust up into her mouth. “Want inside you.”  
  
She pulls off of him with a wet pop, and he grins at her, ready to get what he wants. But then she says, breathless, “Let me just suck you off. I’m on the rag.”  
  
And that has him pulling away from her before he even registers what he’s doing, pushing his legs together and tucking his knees up. She sits up straight and stares back at him, her lips all pouty and red, wet with spit and precome. She looks significantly less than impressed by his reaction.  
  
“You’re kidding me, right?” she says eventually, after she’s stared him down with raised eyebrows for what feels like an eternity. “I have my period, Dean. Not the plague.”  
  
“But--,” Dean starts, gesturing vaguely. “There’s no box.”  
  
She tries to follow his hand gestures, and it obviously takes her a minute to get what he’s referring to. But then she sighs, says, “I just started. Just tonight.”  
  
“Oh,” Dean says, frowning. He cringes at the awkward silence that follows.  
  
“This is why I wasn’t going to say anything,” she finally says, rolling her eyes. She crawls away from him, over to her own side of the bed. “I knew you’d react like this.”  
  
“Then why’d you start this?” Dean says, throwing a hand out to encompass the bed, the almost sex.  
  
“Because I was horny, and I was hoping you’d let me suck you off,” she shoots back, eyes narrowed.  
  
He opens his mouth to say something back but finds that he has no idea what to say. She’s already settled down in the bed anyway, quite pointedly keeping her back turned to him. Dean feels sort of bad for hurting her feelings, even though he didn’t mean to.  
  
He’s also not really sure why he just turned down a free blowjob.  
  
~*~  
  
He dreams that night about diving face-first into her bloody cunt.  
  
It’s all indistinct. Just the blood between her thighs, all over his mouth, against his tongue. The way it tastes and smells. The noises she makes, better than the usual noises she makes when he eats her pussy.  
  
He wakes up lying on his belly, his dick hard as a rock. Sammy’s still asleep, thank God, and he watches the rhythmic inhale, exhale motion of her body for a few moments. He wonders if she’s bleeding heavy or light, thinks he may have just figured out why he’s so uncomfortable about the whole period thing.  
  
He shifts in the bed, rubs against the mattress once, twice, three times, and comes with a muffled grunt into his pillow.  
  
Sammy mumbles in her sleep, but doesn’t wake up.  
  
~*~  
  
It takes him a while to get past the ‘holy shit, I’m really gross’ notion and onto the fact that she’s Sammy, his beautiful sister, and he’s already sort of blown every taboo away by sleeping with her in the first place, so…

He chickens out a few times before he finally gets up the balls to do anything about it. After their spats about it in the past, Dean isn’t sure how Sammy will react, and it makes him a little jumpy. But he picks a night when the tampon box has been out for a few days to start kissing her deep, letting his hands wander down her body, slipping back up under her shirt to fondle her bare breasts.  
  
She moans into his mouth for just a moment before pulling away, looking almost crestfallen. “Dean,” she murmurs.  
  
“I know,” he says quietly, pulling her back to him. “S’okay. I know. I wanna. Wanna try it.”  
  
She’s silent at first, very still, and for a moment Dean thinks she’s going to pull away and tell him to shove it. But then she’s kissing him again, her legs falling open around him. He sighs into her mouth, thinks, _Love you. So much._  
  
He ends up dragging her over to the edge of the bed, her legs dangling off the side, and then kneels down in front of her between her thighs. She watches him tentatively as he drags her panties off and lets the material fall to the floor, and then she’s spread out for him, her pussy soft and pink, the string to the tampon visible between the folds.  
  
He takes a hold of the string and slides the tampon out gently. It smears blood across the crease between her thigh and crotch, and she makes a funny little noise, reaching a hand down to rub at herself. Dean sets the dirty tampon down on top of her underwear—something he’ll probably get yelled at for later, he thinks absently—before he leans forward and presses his mouth against her hand.  
  
Then she moves her hand away and he’s tonguing her cunt, relishing in the quiet happy sigh she gives him in return. She spreads her legs a little wider to give him more room, a hand coming around to cup the back of his head, hips rolling up into his face.  
  
It’s not like he thought it would be. She’s clean against his tongue at first, fairly dry, but then she’d just had the tampon in. He can smell her, though, this rich and earthy smell that has his cock jerking in his underwear. He reaches down to pull himself out of his boxers, starts fucking into his hand.  
  
He has two fingers inside her, working in wet wet heat, when he first tastes that bitter tang of copper on his tongue. It’s like electricity through him, has him removing his fingers to spread her lips and dip his head deeper and fuck her with his tongue. She keens, this sound that Dean knows means she’s close, and he takes his thumb, rubs her clit. Her fingers clutch at his hair.  
  
She’s wet and slippery when she comes, and she grinds down against his face, rubbing dirty and filthy against his tongue. Dean backs away as she’s coming down, moves his face to mouth bloody marks on Sammy’s thigh.  
  
He takes his hand off his cock for long enough to slide it over Sammy’s cunt until it’s covered in blood, then returns it to his cock. Sammy sits up on the bed, watching him silently as he fucks his bloody fist until he comes with a grunt.  
  
He’s left panting, feeling sated and dirty and intimate all at once.  
  
“Figures,” Sammy says after a beat, still sounding breathless and aroused. “Kinky bastard.”  
  
“Bitch,” he mumbles vaguely against her thigh.  
  
She bats him upside the head with her fist, and answers with an affectionate, “Jerk.


End file.
